drop if (exporter=="JPN" | importer=="JPN")
drop if (exporter=="UK" | importer=="UK")
drop if (exporter=="TWN" | importer=="TWN")
drop if (exporter=="CHI" | importer=="CHI")
drop if (exporter=="COL" | importer=="COL")
drop if (exporter=="GUA" | importer=="GUA")
drop if (exporter=="SKO" | importer=="SKO")
drop if (exporter=="COR" | importer=="COR")
drop if (exporter=="RUS" | importer=="RUS")
drop if (exporter=="JAM" | importer=="JAM")
drop if (exporter=="UGA" | importer=="UGA")
drop if (exporter=="JOR" | importer=="JOR")
drop if (exporter=="HON" | importer=="HON")
drop if (exporter=="TNT" | importer=="TNT")
drop if (exporter=="SYR" | importer=="SYR")
drop if (exporter=="SIL" | importer=="SIL")
drop if (exporter=="IRN" | importer=="IRN")
drop if (exporter=="SAF" | importer=="SAF")
drop if (exporter=="GER" | importer=="GER")
drop if (exporter=="IND" | importer=="IND")
drop if (exporter=="SEN" | importer=="SEN")
drop if (exporter=="CHN" | importer=="CHN")
